JP3235635B2 - Inkjet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet apparatus for ejecting ink droplets by contracting a diaphragm constituting a pressure generating chamber connected to a nozzle opening and a common ink chamber by a piezoelectric vibrator in a longitudinal vibration mode. Related to a recording head.

[0002]

2. Description of the Related Art An ink jet recording head using a piezoelectric vibrator in a longitudinal vibration mode as a driving source can reduce the area of the piezoelectric vibrator in contact with a vibration plate.
A high pressure generation chamber arrangement density of at least dpi (dot per inch) is provided. As shown in FIG. 14, such a recording head has a flow path forming plate D provided with a through hole for partitioning a pressure generating chamber A, an ink supply port B, and a common ink chamber C.
And a nozzle plate F having a nozzle opening E communicating with the pressure generating chamber A, and a diaphragm J having a diaphragm portion H elastically deformed by receiving a displacement of the piezoelectric vibrator G. Substrate unit K configured to be liquid-tight
Are fixed to a base L on which a piezoelectric vibrator G, an ink supply pipe and the like are mounted.

In the ink jet recording head configured as described above, the substrate unit is fixed to the base in such a manner that the diaphragm H faces the base so that the diaphragm H comes into contact with the tip of the piezoelectric vibrator G. In order to avoid contact between the base L and the diaphragm H, the pressure generating chamber A
Is fixed to the base L so as to avoid the

In order to increase the arrangement density of the pressure generating chambers in order to increase the resolution, the length of the pressure generating chamber A in the axial direction must be increased because the volume of the pressure generating chamber A must be secured. Since the unsupported area S1 which is not supported by the base L facing the pressure generating chamber A becomes longer, when a certain displacement a is given by the piezoelectric vibrator G to eject ink droplets,
There is a problem that the unsupported area S1 of the substrate unit K easily bends as shown by a dotted line in the figure, which causes a decrease in print quality.

At such a high resolution, the accuracy of the position at which the tip of the piezoelectric vibrator G contacts is a very important requirement. Therefore, as shown in Japanese Patent Application Laid-Open No. 3-15555, the pressure generating chamber is deformed. An island portion M consisting of a thick portion is formed substantially at the center of the deformation region to be
Abutting of the tip of the body. According to such a technique, even if the contact position of the piezoelectric vibrator G is slightly shifted, the displacement of the piezoelectric vibrator G can be transmitted through the island portion M, so that a predetermined displacement can be given to the diaphragm portion H. Becomes

However, if the resolution becomes extremely high, such as 180 dpi or more, an error is likely to occur in the relative position between the island portion M and the pressure generating chamber A, and the deformation state of the pressure generating chamber A varies, thereby deteriorating the printing quality. There is a problem of doing.

Further, since it is necessary to reduce the interval between the pressure generating chambers A, the thickness of the partition walls which partition the pressure generating chambers A is reduced, the rigidity is reduced, and the piezoelectric vibrator for driving the adjacent pressure generating chambers is reduced. There is a problem that the pressure generating chamber is deformed due to expansion and contraction to generate a so-called satellite, and the degree of deformation of the pressure generating chamber due to the expansion of the piezoelectric vibrator is reduced, thereby lowering the ink ejection efficiency.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to reduce the unsupported area of a pressure generating chamber as short as possible. An object of the present invention is to provide an ink jet recording head having improved rigidity. A second object of the present invention is to provide a novel ink jet recording head capable of minimizing the influence of assembly accuracy on print quality.

[0009]

According to the present invention, in order to solve such a problem, a pressure generating chamber, a common ink chamber, and the pressure generating chamber and a common ink chamber are connected.
A flow path forming plate provided with a through hole defining an ink supply port , a nozzle plate provided with a nozzle opening communicating with the pressure generating chamber, and a diaphragm portion elastically deformed by receiving a displacement of the piezoelectric vibrator And a vibration plate provided with a liquid-tightly laminated and fixed substrate unit fixed to a base. mouth side, and the vicinity of the nozzle opening side, rather thick than the diaphragm portion, and the Daiyafu
Wherein to expose the ram portion is thick portion of the extended length is a frame-like to the piezoelectric vibrator side formation, the region opposed to the thick portion of the frame-like is the bonding area of a base I have .

[0010]

The frame-like thick portion extending toward the piezoelectric vibrator is supported on the base to shorten the unsupported area of the pressure generating chamber as much as possible, and the force of the piezoelectric vibrator is applied to the base. It becomes possible to receive, and rigidity increases.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an outline of a recording head according to the present invention. In FIG. 1, reference numeral 2 denotes a nozzle plate having a nozzle opening 1 formed therein, reference numeral 3 denotes a through hole 3a for partitioning a pressure generating chamber 9, and ink supply. A flow path forming plate 4 provided with a through hole or groove 3b for defining the opening 10 and a through hole 3d for defining the common ink chamber 11 is a vibrating plate which elastically deforms by contacting the tip of the piezoelectric vibrator 6. Thus, the nozzle plate 2 and the vibrating plate 4 are fixed to both surfaces of the flow path forming plate 3 in a liquid-tight manner to constitute the substrate unit 5.

Reference numeral 7 denotes a base, into which the piezoelectric vibrator 6 is inserted so as to be able to vibrate. The head 6 and the substrate unit 5 are fixed and integrated into an ink jet recording head. Reference numeral 12 in the figure denotes an ink supply pipe that supplies ink from an ink tank (not shown) to the substrate unit 5.

FIG. 2 shows an embodiment of the above-described piezoelectric vibrator 6, in which a piezoelectric material layer 60 and electrode layers 61 and 62 are shown.
Are alternately stacked in multiple layers, and each of the electrode layers 61, 6
2 is connected to a segment electrode 63 for receiving a signal from an external drive source and a common electrode 64 at both ends, and is configured to expand and contract in a direction parallel to the electrode layers 61 and 62. .

FIG. 3 is a diagram showing the mounting state of the above-mentioned substrate unit 5 and the piezoelectric vibrator 6. The nozzle plate 2 and the vibrating plate 4 are liquid-tight on both sides of the flow path forming plate 3. The pressure generating chamber 9 is formed along the direction in which the nozzle openings 1 are arranged by fixing the pressure generating chamber 9 with an adhesive.

On the other hand, the vibrating plate 4 is formed with an island portion 4a which is in contact with the tip of the piezoelectric vibrator 6 so as to be located substantially at the center of the region facing the pressure generating chamber 9, and has an adjacent pressure generating region. The first thick portion is opposed to the partition wall 3c separating the chamber 9 and coincides with the boundary of the pressure generating chamber 9 or slightly bites into the inside of the pressure generating chamber 9 as shown in FIG. 4b and second and third thick portions 4c and 4d are formed so as to slightly bite into both ends of the pressure generating chamber 9, and these island portions 4a and the first, second and third thick portions are formed. A diaphragm portion 4e in which a thin region surrounded by the portions 4b, 4c, and 4d is deformed by the piezoelectric vibrator 6.
It is partitioned as.

The diaphragm portion 4e is formed to be slightly smaller than the opening of the pressure generating chamber 9 as shown in FIG. 4, and the thick portions 4b, 4c, 4d of the diaphragm 4 are moved to the pressure generating chamber 9 side. The first thick portion 4b
Is Δ from the wall 3c defining the pressure generation chamber to the pressure generation chamber 9 side.
L1 (FIG. 5), and the second and third thick portions 4c and 4d also approach the pressure generating chamber by ΔL2 near both ends of the pressure generating chamber (FIG. 6).

As an example, the width W of the pressure generating chamber 9 will be described.
1 to 200 μm, and the width W2 of the partition 3c to 80 μm
Further, when the width W3 of the first thick portion 4b is set to 140 μm, the center line of the pressure generating chamber 9 and the center line of the island portion 4a coincide, and the flow path forming plate 3 and the diaphragm 4 are joined. 30 μm as the length of protrusion ΔL1
Can be secured.

As a result, as shown in FIG. 7, even if the positioning error .DELTA.L3 between the flow path forming plate 3 and the diaphragm 4 becomes 20 .mu.m, the diaphragm portion 4a is positioned so as to face the pressure generating chamber 9. , The adhesive P protruding region L4
To 10 μm. As a result, even if the adhesive P protrudes from the partition wall 3c, the first,
The absorption by the second and third thick portions 4b, 4c and 4d and the flow out to the diaphragm portion 4e can be prevented, and the elastic characteristics of the diaphragm portion 4e can be made constant.

That is, the thick portion 4b is connected to the partition wall 3 of the pressure generating chamber 9.
When the gap is formed between the diaphragm 4 and the flow path forming plate 3 so as to match the width of the diaphragm c, the adhesive P flows out to the diaphragm portion 4e as shown in FIG. The vibration characteristics of the portion 4e will be changed.

Generally, the width W3 of the first thick portion 4b opposed to the partition wall 3c is about 5 to 50% of the width W2 of the partition wall 3c which partitions the adjacent pressure generating chambers 9 from each other. When the size is increased, the assembly error can be absorbed, and the ink ejection performance can be made constant.

On the other hand, the diaphragm portion 4e has a frame-like second and third thick portion 4c having substantially the same thickness as the island portion 4a, and a diaphragm 3c of the pressure generating chamber 9 which is integrally formed with the frame portion. The first thick portion 4b of the diaphragm 4 is reinforced by the first thick portion 4b of the diaphragm 4 in addition to the nozzle plate 2 because the first thick portion 4b extends in parallel with the first thick portion 4b. As a result, the rigidity of the entire substrate unit 5 with respect to the displacement of the piezoelectric vibrator 6 is increased, and the deflection of the substrate unit 5 during ink ejection is suppressed as small as possible, thereby preventing crosstalk.

Further, as shown in FIG. 8, the piezoelectric vibrator 6 has the second and third thick portions 4c and 4d formed at both ends of the pressure generating chamber 9 along the partition walls 3c of the pressure generating chamber 9. The extended area (the area shown by filling in dots in FIG. 3) is fixed to the base 7 with an adhesive and supported by the base 7, so that the unsupported area S2 is Therefore, the deflection of the entire substrate unit 5 due to the displacement of the piezoelectric vibrator 6 is reduced.

The diaphragm 4 is formed of a polymer film of polyimide, polysulfone, polycarbonate, polyetherimide, polyethylene, polyaramid, polyester, or the like, and nickel and chromium in the regions where the island portions 4a and the thick portions 4b, 4c, and 4d are formed. Or the like, or the polymer film is laminated on a metal film such as nickel, chromium, stainless steel, gold, silver, copper, or titanium by casting or the like, and the metal film is formed in the island portion 4a, the thick portion 4b, It can be manufactured by etching according to the shapes of 4c and 4d, or by partially etching the region to be the diaphragm portion 4a using a metal film of silicon, nickel, chromium, stainless steel, titanium or the like.

In this embodiment, a stainless steel film having a thickness of 40 μm and a polyimide film having a thickness of 3 μm are joined and laminated, and the stainless steel is etched.

FIG. 9 shows a second embodiment of the present invention. In this embodiment, of the first thick portion formed on the diaphragm 3, the vicinity of both ends of the pressure generating chamber 9 is shown. (A,
Only the region B is overhanged to the pressure generating chamber side, and the width of the region facing the island portion 4e (the region C in the figure) is made equal to the width of the partition wall 3c defining the pressure generating chamber 9. ing.

According to this embodiment, as long as the positioning accuracy between the diaphragm 4 and the flow path forming plate 3 is increased, a large area of the diaphragm portion 4e can be ensured, and the fixed area by the base 7 can be as large as possible. In other words, the non-support area S2 can be shortened, and the deflection of the flow path unit 5 can be reduced.

FIG. 10 shows a third embodiment of the present invention. In this embodiment, the second and third thick portions 4c and 4d formed near both ends of the pressure generating chamber 9 are shown. To the extent that it reaches both ends of the island portion 4a (reference numerals A and B in the figure).
In this embodiment, the first thick portion 4b is eliminated to form a thin portion 4f, and according to this embodiment, the support area of the base 7 is as large as possible. While reducing the deflection of the board unit 5
When the adhesive for bonding to the base 7 is applied by transfer, the application area can be limited only to the thick portion of the peninsula, and the flow of the adhesive for fixing to the base 7 can be reduced. It can be prevented as much as possible from reaching the diaphragm part 4e.

In this embodiment, the base 7 and the thick portion 4c
The base 4 and the island portion 4a are joined so that the vibration plate 4 does not come into contact with the vibration during the ink discharging operation.
This is performed in a region inside the pressure generating chamber 9 and outside both ends of the island portion 4a.

FIG. 11 shows a fourth embodiment of the present invention. In this embodiment, the second and third thick portions 4c and 4d formed on the above-mentioned peninsula are continuous with each other. In the region (reference numeral C in the figure) facing the island portion, the partition 3c
The first thick portion 4b is configured to be slightly smaller than the width of the first thick portion. According to this embodiment, it is possible to improve the rigidity of the entire substrate unit and to prevent the deflection by extending the support area by the base 7 while keeping the area of the diaphragm portion 4e as large as possible.

In the above-described embodiment, an example has been described in which the piezoelectric vibrator in the longitudinal vibration mode is used as the driving source. However, a piezoelectric vibrator in the flexural vibration mode can be used.

That is, as shown in FIG. 12, the island portion 4a is not formed on the surface of the diaphragm portion 4e defined by the thick portions 4b, 4c and 4d.
By attaching the piezoelectric vibrator 20 in the flexural vibration mode so as not to contact the thick portions 4b, 4c, and 4d, the diaphragm portion 4e is deformed, and the flow path forming plate 21, the second lid plate 24, and the vibration The pressure generating chamber 23 formed by the plate 4 is contracted and ink is ejected from the nozzle opening 22 communicating with the pressure generating chamber 23. In this embodiment as well, propagation of vibration to the adjacent pressure generating chamber 23 is increased. Parts 4b, 4c, 4d
Can be prevented. Note that reference numeral 25 in the drawing denotes an ink supply port.

[0032]

As described above, according to the present invention, the pressure generating chamber, the ink supply port, and the flow path forming plate provided with the through holes for defining the common ink chamber are communicated with the pressure generating chamber. Plate unit with a nozzle plate with a perforated nozzle opening and a diaphragm with a diaphragm that elastically deforms in response to the displacement of the piezoelectric vibrator, and is fixed in a liquid-tight manner with an adhesive. In the ink jet recording head fixed to the table, the vibration plate, at least in the vicinity of the ink supply port side of the pressure generating chamber, and the nozzle opening side,
Since a frame-shaped thick portion thicker than the diaphragm portion is formed, and a region facing the frame-shaped thick portion is an adhesion region with a base, without disturbing the displacement of the diaphragm portion, The unsupported region of the pressure generating chamber can be shortened, and the deflection of the substrate unit due to the displacement of the piezoelectric vibrator can be reduced.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head of the present invention.

FIG. 2 is a sectional view showing one embodiment of a piezoelectric vibrator used in the head.

FIG. 3 is an enlarged partial cross-sectional perspective view showing a contact area between a substrate unit of the head and the piezoelectric vibrator.

FIG. 4 is a diagram showing a relative position between a flow path forming plate and a diaphragm of the head.

FIG. 5 is a sectional view taken along line AA in FIG. 4;

FIG. 6 is a sectional view taken along line BB in FIG. 4;

FIG. 7 is a cross-sectional view showing a case where an error occurs in the positioning of the diaphragm and the flow path forming plate during assembly of the head, and a state in which an adhesive for joining the two protrudes.

FIG. 8 is a diagram showing a structure in a cross section along an axis of the pressure generating chamber.

FIG. 9 is a diagram showing a second embodiment of the present invention with a top structure of a diaphragm.

FIG. 10 is a view showing a third embodiment of the present invention with a top structure of a diaphragm.

FIG. 11 is a view showing a fourth embodiment of the present invention with a top structure of a diaphragm.

FIG. 12 is a diagram showing an embodiment in which a flexural vibration piezoelectric vibrator is applied.

FIGS. 13A and 13B are a cross-sectional view showing an example of a conventional ink jet recording head and a diagram schematically showing the protrusion of an adhesive.

FIG. 14 is a diagram illustrating an example of a conventional inkjet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle opening 2 Nozzle plate 3 Flow path forming plate 4 Vibration plate 4a Island part 4b First thick part 4c Second thick part 4d Third thick part 4e Diaphragm part 5 Substrate unit 6 Piezoelectric vibrator 7 base Table 8 Fixed unit 9 Pressure generation chamber 10 Ink supply port 11 Common ink chamber

Continuing on the front page (72) Inventor Kazuhiko Miura 3-3-5 Yamato, Suwa-shi, Nagano Inside Seiko Epson Corporation (72) Inventor Takahiro Naka 3-3-5 Yamato, Suwa-shi, Nagano Prefecture Seiko Epson shares In-company (56) References JP-A-5-169651 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (8)

(57) [Claims] A pressure generating chamber, a common ink chamber, and a flow path forming plate provided with a through hole for defining an ink supply port connecting the pressure generating chamber and the common ink chamber; A base plate is constructed by liquid-tightly laminating and fixing a nozzle plate having a nozzle opening communicating with a chamber and a diaphragm having a diaphragm portion elastically deformed by displacement of a piezoelectric vibrator. In the ink jet recording head fixed to, the diaphragm is thicker than the diaphragm portion near the ink supply port side and the nozzle opening side of the pressure generating chamber, and is configured to expose the diaphragm portion. An ink jet recording head, wherein a frame-shaped thick portion extended to the piezoelectric vibrator side is formed, and a region facing the frame-shaped thick portion is an adhesion region with a base. 2. An ink jet recording head according to claim 1, wherein an island portion formed of a thick portion is formed in a region facing said piezoelectric vibrator. 3. The ink jet recording head according to claim 1, wherein said frame-shaped thick portion is extended so as to face a partition partitioning said pressure generating chamber. 4. The ink jet recording head according to claim 1, wherein the thick portion is interrupted in a region facing the piezoelectric vibrator. 5. The ink jet recording head according to claim 1, wherein a width of said thick portion is set to be smaller than a width of a partition partitioning said pressure generating chamber. 6. A flow path forming plate having a pressure generation chamber, a common ink chamber, and a through hole for defining an ink supply port connecting the pressure generation chamber and the common ink chamber, and the pressure generation chamber. Ink jet recording in which a nozzle plate having a nozzle opening communicating with a chamber is laminated with a diaphragm having a diaphragm portion that is elastically deformed by displacement of a piezoelectric vibrator, and is fixed in a liquid-tight manner with an adhesive. In the head, the vibrating plate includes a frame-shaped thick portion that is thicker than the diaphragm portion, at least near the ink supply port side and the nozzle opening side of the pressure generating chamber, and the thick portion has the pressure. An ink jet recording head that is overhanging on the generation chamber side. 7. The width of the thick portion in a region facing the partition that partitions the pressure generating chamber is set to be 5 to 50% wider than the width of the partition that partitions the pressure generating chamber. Inkjet recording head. 8. The ink jet recording head according to claim 6, wherein the piezoelectric vibrator side from both ends of the pressure generating chamber is a bonding area with the base.